Internal combustion engines, such as used in motorcycles or automobiles, require fuel to operate. The fuel is generally stored in a fuel tank, located a distance from the engine, and is pumped to the engine. Fuel delivery systems for pumping the fuel to the engine are either closed-loop systems or open-loop systems. In an open-loop system, a fuel pump is operated at a constant rate to provide sufficient fuel to the engine for all operating conditions. When less fuel is required than is provided by the fuel pump, the excess fuel is returned to the fuel tank.
In a closed-loop system, there is no return path for fuel back to the fuel tank. Instead, the fuel pump is controlled to provide fuel to the engine at a constant pressure regardless of the quantity of fuel used by the engine.